/Engine/Source/Runtime/StaticMeshDescription/Public/StaticMeshOperations.h
Set the triangle tangent, normal, binormal and triangleCenter for all triangles in the mesh description.
static void ComputeTriangleTangentsAndNormals ( [FMeshDescription](API\Runtime\MeshDescription\FMeshDescription) & MeshDescription, float ComparisonThreshold, const TCHAR * DebugName )